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Compact short back focus imaging lens system with two lenses

a short back focus and imaging lens technology, applied in the field of compact short back focus imaging lens system with two lenses, can solve the problems of reducing the overall length of these imaging lens systems, affecting the quality of the image, and the difficulty of adjusting the focal length of the imaging lens, so as to achieve short back focal length, short overall length, and low cost

Inactive Publication Date: 2011-09-20
E PIN OPTICAL IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The present invention provides a compact imaging lens system with two lenses that have a short back focus and low cost. The lens system satisfies certain conditions, such as the distance between the lenses, the back focal length, the total length, and the radius of curvature of the lens surfaces. The lens system can be made from glass or plastic. The technical effects of the invention are a short overall length and a broader range of applications."

Problems solved by technology

However, the overall length of these imaging lens systems still requires further improvement to be reduced.
But the design with reducing the back focal length will cause the difficulty for adjusting the focal length of the imaging lens.

Method used

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  • Compact short back focus imaging lens system with two lenses
  • Compact short back focus imaging lens system with two lenses
  • Compact short back focus imaging lens system with two lenses

Examples

Experimental program
Comparison scheme
Effect test

first embodiment

The First Embodiment

Refer to FIG. 2-5, show the optical path and field curvature, distortion and vertical aberration (while radius is 0.6086 mm) of image of this embodiment, respectively.

List 1:fs = 3.408SurfaceLensRdNdυdObject∞1(Stop)*R10.94510.8311.58760.02*R21.47490.6063*R3−2.60891.1331.58760.04*R4−4.23560.3305R5∞0.5001.51764.176R6∞0.363Image∞*aspherical surface

List 2:KA4A6A8A10A12A14*R17.2509E−02−1.2766E−011.7993E+00−1.4137E+015.9805E+01−1.3135E+021.1763E+02*R28.4914E+004.4620E−025.4374E−01−1.5469E+004.1302E+00−2.4597E+000.0000E+00*R31.4394E+01−1.8524E−01−5.0197E−011.1023E+00−1.9051E+000.0000E+000.0000E+00*R41.8819E+00−2.8780E−02−8.5916E−02−3.1650E−022.2916E−01−2.6495E−011.2800E−01

In this embodiment, the first lens 11 and the second lens 12 are made from the same glass with the refractive index Nd of 1.587 and Abbe's number νd1 of 60.0. The IR cut-off filter 13 is made from glass with the refractive index Nd of 1.517 and Abbe's number νd1 of 64.17.

The fs is 3.408 mm, f1 is 2.787...

second embodiment

The Second Embodiment

Refer to FIG. 2&FIG. 6-8.

List 3fs = 3.129SurfaceLensRdNdυdObject∞1(Stop)*R10.93710.8241.58760.02*R21.50000.4523*R3−3.32051.0851.58760.04*R4−3.89010.3135R5∞0.7001.51764.176R6∞0.222Image∞*aspherical surface

List 4KA4A6A8A10A12A14*R13.0726E−01−1.2599E−011.8009E+00−1.4144E+015.9403E+01−1.3158E+021.2121E+02*R22.2171E+004.1705E−025.4018E−01−1.5075E+008.2928E+00−6.5863E+000.0000E+00*R31.2770E+01−1.8944E−01−5.1639E−011.0845E+00−2.4199E+000.0000E+000.0000E+00*R41.5449E+01−3.0803E−02−8.6594E−02−3.2235E−022.2793E−01−2.6552E−011.2771E−01

In this embodiment, the first lens 11 and the second lens 12 are made from the same glass with the refractive index Nd of 1.587 and Abbe's number νd1 of 60.0. The IR cut-off filter 13 is made from glass with the refractive index Nd of 1.517 and Abbe's number νd1 of 64.17.

The fs is 3.129 mm, f1 is 2.7719 mm, f2 is −130.8 mm, TL is 3.5959 mm, satisfying from the equation (1) to the equation (4).

d2+d4+d6fs=0.3155;f1f2=-0.0212;bfTL=0.3946;(R2-R3)...

third embodiment

The Third Embodiment

Refer to FIG. 2&FIG. 9-11.

List 5fs = 2.878Surface$L$ensRdNdυdObject∞1(Stop)*R10.86970.6921.58058.92*R21.53530.5123*R3−4.73621.1251.58058.94*R4−19.04320.1005R5∞0.7001.51764.176R6∞0.222Image∞*aspherical surface

List 6KA4A6A8A10A12A14*R11.6398E−01−1.2320E−018.7112E−01−3.7158E+002.6497E+002.7326E+002.0840E+01*R26.0971E+002.6171E−01−1.6968E+001.1420E+01−4.2238E+00−1.1136E+022.2379E+02*R3−3.1297E+02−2.7133E−01−1.7717E+007.9263E+00−9.4245E+00−4.5828E+011.4460E+02*R48.5842E+01−4.8528E−02−1.0180E−017.5329E−02−2.6834E−02−1.0559E−04−3.8768E−04

In this embodiment, the first lens 11 and the second lens 12 are made from the same glass with the refractive index Nd of 1.580 and Abbe's number νd1 of 58.9. The IR cut-off filter 13 is made from glass with the refractive index Nd of 1.517 and Abbe's number νd1 of 64.17.

The fs is 2.878 mm, f1 is 2.4924 mm, f2 is −11.1504 mm, TL is 3.3509 mm, satisfying from the equation (1) to the equation (4).

d2+d4+d6fs=0.2898;f1f2=-0.2235;bfTL=0.3551...

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Abstract

A compact short back focus imaging lens system with two lenses is revealed and includes along the optical axis from an object side to an image side: an aperture stop, a first lens with positive refractive power that is a meniscus aspherical lens with convex surface facing the object side, a second lens with negative refractive power that is a meniscus aspherical lens with convex surface facing the image side, an IR cut-off filter and an image sensor. Moreover, the following conditions are satisfied by the imaging lens system:-0.3≤f1f2≤-0.010.25≤bfTL≤0.4wherein f1 is focal length of the first lens, f2 is focal length of the second lens, bf is back focal length of the imaging lens system, and TL (overall length) is the distance from the aperture stop to the image plane. Thus, the imaging lens system of the present invention has short back focal length effects and reduced overall length so as to achieve the requirement of minimized volume for mobile phones or mini-cameras.

Description

BACKGROUND OF THE INVENTIONThe present invention relates to a compact short back focus imaging lens system with two lenses, especially to an imaging lens system for mini-cameras or mobile phones with image sensors such as CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor), which is formed by one positive lens and one negative lens and is with features of short back focal length, short overall (total) length and low cost.The electronics available now become more compact and multifunctional. Most of them such as digital still cameras, PC (personal computer) cameras, network cameras and mobile phones, even personal digital assistants (PDA) are equipped with an imaging lens system. The imaging lens system not only requires good imaging quality but also needs compact volume (short overall length) and lower cost so as to match users' requirements.There are various designs such as two lenses, three lenses, four lenses or five lenses of the imaging lens system app...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G02B13/18G02B9/04
CPCG02B9/10G02B13/003G02B13/18G02B5/282G02B7/021G03B30/00H04N23/55
Inventor WU, CHIEN-LINSHYU, SAN-WOEI
Owner E PIN OPTICAL IND